1) drawbitmap(string file,int x,int y): draw a bitmap that's in the Windows bitmap file format (*.bmp; *.2bp). it supports 2;4;8 bit indexed colors and True color bitmaps. even if it's compressed.
2) drawbitblt(string file,int x,int y,int flag): same as 1) but plot the point of the bitmap with a special opertaor (flag).
It goes so:
i.e. if the operator is XOR, the point from the bitmap is red,
and the point on the screen is white:
bitmap |XOR| screen | result
===============================================
R:11111111 |XOR|11111111 |00000000
G:00000000 |XOR|11111111 |11111111
B:00000000 |XOR|11111111 |11111111

and so it makes CYAN.

sometimes it makes more than one operator (i.e. bitmap AND (NOT screen) ).
You can find in the V3 documentation which flag makes which operation.

3) drawimage(string file,int x,int y,int w,int h,int sizeratio,int flag) can draw not compressed windows bitmap (*.bmp, *.2bp); JPEG bitmaps(*.jpg) and Compuserve GIF (*.gif). It has the same flag than the 2) and it's able to minimize the size of the image (with w an h or sizeratio).